This invention relates to load centers for electric power distribution systems and more particularly to the bus bars and plug-in contact stabs for bus bars used in such systems. Still more particularly, this invention is an improvement over the invention disclosed in U.S. Pat. No. 4,002,388 issued Jan. 11, 1977, to G. A. Menocal entitled Stab Arrangement For Busbars.
The present invention is particularly adapted for use in a load center of the type shown in U.S. Pat. No. 3,349,292 issued Oct. 24, 1967, to James F. Meacham, and this patent is incorporated herein by reference, particularly with respect to its showing of an environment in which the present invention may be used and for its description of an arrangement of bus bars in single phase and three phase installations. See also U.S. Pat. Nos. 3,402,328 and 3,767,977.
A bus bar contact stab structure of the type adapted for the present invention comprises an elongated strip or ribbon of conductive material designated the bus bar. Projecting forward of the bus bar at spaced intervals along its longitudinal axis and laterally spaced therefrom are a plurality of stab connections to be plugged into stab receiving cooperating contacts at the line side of a circuit breaker, or the like equipment. Hereinafter, a circuit breaker is described as the equipment to be mechanically and electrically plugged onto a bus bar stab. But it should be understood that other electrical equipment having appropriate contact means may be plugged onto the stab.
A circuit breaker line contact which receives a bus bar stab may be comprised of a U-shaped clip having two arms which open outwardly of the breaker and are normally spaced apart a distance such that the stab must be forced between the arms of the clip. The clip arms are inwardly biased against the stab to make secure mechanical and electrical contact.
There are different manufacturers of circuit breakers, different sizes of circuit breakers, different styles of circuit breakers and different current ratings of circuit breakers. As a result, there are common use circuit breakers having stab receiving line contacts consisting of clip arms defining an opening between them that is oriented parallel to the long or length dimension of the circuit breaker (see U.S. Pat. Nos. 3,402,328 and 3,349,292). Other circuit breakers are available having stab receiving line contacts consisting of clip arms defining an opening between them that is oriented parallel to the narrower or width dimension of the circuit breakers (see U.S. Pat. No. 3,767,977). Furthermore, the former type circuit breakers have conventionally been placed in one inch wide casings while the latter type circuit breakers have been placed in half inch wide casings.
Commercially available panelboards having male plug-in stabs are usually constructed with bus bars having a plurality of stabs, with each stab adapted to receive only one type of circuit breaker, i.e., with its line contacts oriented in only one direction and/or where the circuit breakers have half inch wide or inch wide casings. (See U.S. Pat. No. 3,333,157 for one effort to deal with this problem.) Furthermore, each such bus bar stab is usually able to support only one circuit breaker extending away from the stab in one direction and is not able to support two neighboring circuit breakers extending in the same direction.